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The International Space Station (ISS) requires advanced life support to continue its mission as a permanently-manned space laboratory and to reduce logistic resupply requirements as the Space Shuttle retires from service. Additionally, as humans reach to explore the moon and Mars, advanced vehicles and extraterrestrial bases will rely on life support systems that feature in-situ resource utilization to minimize launch weight and enhance mission capability. An obvious goal is the development of advanced systems that meet the requirements of both mission scenarios to reduce development costs by deploying common modules. A high pressure oxygen generating assembly (HPOGA) utilizing a high differential pressure (HDP) water electrolysis cell stack can provide a recharge capability for the high pressure oxygen storage tanks on-board the ISS independently of the Space Shuttle as well as offer a pathway for advanced life support equipment for future manned space exploration missions.

The central objective of the Earth-Moon-Mars Radiation Environment Module (EMMREM) project is to develop and validate a numerical module for completely characterizing time-dependent radiation exposure in the Earth-Moon-Mars and Interplanetary space environments. An important step in the process of building this system is the development of the interfaces between EMMREM's internal components, many of which have existed previously as stand-alone simulation codes. This work specifically discusses the development and implementation of the interface, primarily using the Perl scripting language, between two input data set generators, one of which describes the space radiation environment at some desired location, and a space radiation transport and shielding code, BRYNTRN, that provides estimates at fairly short time intervals of dose and dose equivalent behind shielding.

Electrical disturbances caused by charging of cables in spacecraft can impair electrical systems for long periods of time. The charging originates primarily from electrons trapped in the radiation belts of the earth. The model Space Electrons Electromagnetic Effects (SEEE) is applied in computing the transient charge and electric fields in cables on spacecraft at low to middle earth altitudes. The analysis indicated that fields exceeding dielectric breakdown strengths of common dielectric materials are possible in intense magnetic storms for systems with inadequate shielding. SEEE also computes the minimal shielding needed to keep the electric fields below that for dielectric breakdown.

Long-term exposure to the space radiation environment poses deleterious effects to both humans and space systems. The major sources of the radiation effects come from high energy galactic cosmic radiation and solar proton events. In this paper we investigate the radiation-mitigation properties of several shielding materials for possible use in spacecraft design, surface habitats, surface rovers, spacesuits, and temporary shelters. A discussion of the space radiation environment is presented in detail. Parametric radiation shielding analyses are presented using the NASA HZETRN 2005 code and are compared with ground-based experimental test results using the Loma Linda University Proton Therapy facility.

The second generation International Space Station (ISS) Total Organic Carbon Analyzer's (TOCA) function is to monitor concentrations of Total Organic Carbon (TOC) in ISS water samples. TOC is one measurement that provides a general indication of overall water quality by indicating the potential presence of hazardous chemicals. The data generated from the TOCA is used as a hazard control to assess the quality of the reclaimed and stored water supplies on-orbit and their suitability for crew consumption. This paper details the unique ISS Program requirements, the design of the ISS TOCA, and a brief description of the on-orbit concept-of-operations. The TOCA schematic will be discussed in detail along with specific information regarding key components.

A growing body of evidence supports an ancient Mars having a milder, wetter climate, suggesting that its atmosphere was once more substantial than it is today. The fate of the lost atmosphere and water is a major unanswered question. Is the “lost” water sequestered in the crust at all latitudes, or did much of it escape to space? While available measurements and theoretical studies suggest that a number of atmospheric escape processes are at work today, little is known about their efficacy, including temporal variations driven by the solar cycle and Mars seasons. Selected 3-D simulations are presented and illustrate the coupling between the thermosphere-ionosphere system and the exosphere leading to predictions of the oxygen corona and hot oxygen escape (a major component of atmospheric loss for present day Mars).

Exposure to microgravity during space flight causes bone loss when calcium and other metabolic by-products are excreted in urine voids. Frequent and accurate measurement of urine void volume and constituents is thus essential in determining crew bone loss and the effectiveness of the countermeasures that are taken to minimize this loss. Earlier space shuttle Urine Monitoring System (UMS) technology was unable to accurately measure urine void volumes due to the cross-contamination that took place between users, as well as to fluid system instabilities. Crew urine voids are currently collected manually in a flexible plastic bag that contains a known tracer quantity. A crew member must completely mix the contents of this bag before withdrawing a representative syringe sample for later ground analysis. The existing bag system accuracy is therefore highly dependent on mixing technique.

As the United States makes plans to return astronauts to the moon and eventually send them on to Mars, designing the most effective, efficient, and robust spacesuit life support system that will operate successfully in dusty environments is vital. Some knowledge has been acquired regarding the contaminants and level of infiltration that can be expected from lunar and Mars dust, however, risk mitigation strategies and filtration designs that will prevent contamination within a spacesuit life support system are yet undefined. A trade study was therefore initiated to identify and address these concerns, and to develop new requirements for the Constellation spacesuit element Portable Life Support System. This trade study investigated historical methods of controlling particulate contamination in spacesuits and space vehicles, and evaluated the possibility of using commercial technologies for this application. The trade study also examined potential filtration designs.

This paper summarizes the activities of the University of Maryland Space Systems Laboratory in performing a design study for a minimum functionality lunar habitat element for NASA's Exploration Systems Mission Directorate. By creating and deploying a survey to personnel experienced in Earth analogues, primarily shipboard and Antarctic habitats, a list of critical habitat functions was established, along with their relative importance and their impact on systems design/implementation. Based on a review of relevant past literature and the survey results, four habitat concepts were developed, focused on interior space layout and preliminary systems sizing. Those concepts were then evaluated for habitability through virtual reality (VR) techniques and merged into a single design. Trade studies were conducted on habitat systems, and the final design was synthesized based on all of the results.

Operational issues encountered by Apollo astronauts relating to lunar dust were catalogued, including material abrasion that resulted in scratches and wear on spacesuit components, ultimately impacting visibility, joint mobility and pressure retention. Standard methods are being developed to measure abrasive wear on candidate construction materials to be used for spacesuits, spacecraft, and robotics. Calibration tests were conducted using a standard diamond stylus scratch tip on the common spacecraft structure aluminum, Al 6061-T6. Custom tips were fabricated from terrestrial counterparts of lunar minerals for scratching Al 6061-T6 and comparing to standard diamond scratches. Considerations are offered for how to apply standards when selecting materials and developing dust mitigation strategies for lunar architecture elements.

Humidity control within confined spaces is of great importance for current NASA environmental control systems and future exploration applications. The engineered multifunction surfaces (MFS) developed by ORBITEC is a technology that produces hydrophilic and antimicrobial surface properties on a variety of substrate materials. These properties combined with capillary geometry create the basis for a passive condensing heat exchanger (CHX) for applications in reduced gravity environments, eliminating the need for mechanical separators and particulate-based coatings. The technology may also be used to produce hydrophilic and biocidal surface properties on a range of materials for a variety of applications where bacteria and biofilms proliferate, and surface wetting is beneficial.

A long-duration lunar outpost will rely entirely upon imported or preserved foods to sustain the crew during early Lunar missions. Fresh, perishable foods (e.g. salad crops) would be consumed by the crew soon after delivery by the re-supply missions, and can provide a supplement to the diet rich in antioxidants (bioprotectants) that would serve as a countermeasure to radiation exposure. Although controlled environment research has been carried out on the growth of salad crops under a range of environmental conditions, there has been no demonstration of sustainable production in a flight-like system under conditions that might be encountered in space. Several fundamental challenges that must be overcome in order to achieve sustained salad crop production under the power, volume and mass constraints of early Lunar outposts include; growing multiple species, sustaining productivity through multiple plantings, and minimizing time for crew operations.

The design and evaluation of a Vacuum-Swing Adsorption (VSA) system to remove metabolic water and metabolic carbon dioxide from a spacecraft atmosphere is presented. The approach for Orion and Altair is a VSA system that removes not only 100 percent of the metabolic CO2 from the atmosphere, but also 100% of the metabolic water as well, a technology approach that has not been used in previous spacecraft life support systems. The design and development of an Orion Crew Exploration Vehicle Sorbent Based Atmosphere Revitalization system, including test articles, a facility test stand, and full-scale testing in late 2008 and early 2009 is discussed.

The system dependency analysis for complex aircraft systems is a model-based methodology and tool for analyzing availability and minimum acceptable control requirements for failures or event scenarios to support the aircraft and system safety analyses (SAE ARP4761) required to show compliance to 14CFR/CS §25.1309, §25.671 and others. Aspects of the system such as functional interaction and dependencies to supply systems, physical items (equipment, wiring and tubing) and installation aspects are included in the analysis. The SAE paper “System Dependency Analysis for Complex Aircraft Systems” (2007-01-3852) describes the modeling approach and the analysis of system dependencies supporting the aircraft and system safety analyses. This paper provides examples for using the system dependency analysis to support the common cause analyses (SAE ARP4761) for complex aircraft systems.

In this paper, the numerical analysis of a three-point bending test of an aluminum foam sandwich structure is performed with the new extended finite element feature supported by Abaqus 6.9. The sandwich beam consists of two aluminum skins and one aluminum foam core. Three different sets of model dimensions are selected for comparison with the reference results (J. Yu, E. Wang, J. Li, Z. Zheng, “Static and low-velocity impact behavior of sandwich beams with closed-cell aluminum-foam core in three-point bending”, International Journal of Impact Engineering, 35, 2008, pp 885-894). Failure modes in this paper can be categorized into three parts: face yield (FY), indentation (IN), and core shear (CS). Face yield occurs on the surface of the core when the thickness of the skin is small. Indentation and core shear occur if the thickness of the skin is relatively large.

Drilling fastener holes in composite is much more difficult than in aluminum or other metallic materials since individual carbon fibers fracture at irregular angles resulting in numerous microscopic voids. These voids can trap excess sealant inhibiting the intimate electrical contact between the fastener and the composite structure. As the cutting tool wears there is an increase of surface chipping and an increase in the amount of uncut fibers or resin. This condition is referred to as machining–induced micro texture. Machining–induced micro texture has been shown to be associated with the presence of arcing between the fastener and the composite structure during lightning strike tests. Lightning protection of composite structure is more complex due to the intrinsic high resistance of carbon fibers and epoxy, the multi-layer construction and the anisotropic nature of the structure.

A consortium of interested parties has conducted an experimental characterization of two Tau parallel kinematic machines which were built as a part of the EU-funded project, SMErobot1. Characteristics such as machine stiffness, work envelope, repeatability and accuracy were considered. This paper will present a brief history of the Tau parallel machine, the results of this testing and some comment on prospective application to the aerospace industry.

Data mining is defined as the discovery of useful, possibly unexpected, patterns and relationships in data using statistical and non-statistical techniques in order to develop schemes for decision and policy making. Data mining can be used to discover the sources and causes of problems in complex systems. In addition, data mining can support simulation strategies by finding the different constants and parameters to be used in the development of simulation models. This paper introduces a framework for data mining and its application to complex problems. To further explain some of the concepts outlined in this paper, the potential application to the NASA Shuttle Reinforced Carbon-Carbon structures and genetic programming is used as an illustration.

The electrical and mechanical failures (such as bearing and winding failures) combine to cause premature failures of the generators, which become a flight safety issue forcing the crew to land as soon as practical. Currently, diagnostic / prognostic technologies are not implemented for aircraft generators where repairs are time consuming and its costs are high. This paper presents the development of feature extraction and diagnostic algorithms to ultimately 1) differentiate between these failure modes and normal aircraft operational modes; and 2) determine the degree of damage of a generator. Electrical signature analysis based features were developed to distinguish between healthy and degraded generators while taking into account their operating conditions. The diagnostic algorithms were developed to have a high fault / high-hour detection rate along with a low false alarm rate.

An aircraft environmental control system (ECS) is commonly designed for a cabin that has been divided into several thermal control zones; each zone has an air flow network that pulls cabin air over an isolated thermocouple. This single point measurement is used by the ECS to control the air temperature and hence the thermal environment for each zone. The thermal environment of a confined space subjected to asymmetric thermal loads can be more fully characterized, and subsequently better controlled, by determining its “equivalent temperature.” This paper describes methodology for measuring and controlling cabin equivalent temperature. The merits of controlling a cabin thermal zone based on its equivalent temperature are demonstrated by comparing thermal comfort, as predicted by a “virtual thermal manikin,” for both air-temperature and equivalent-temperature control strategies.